8mm Forum: What Causes A Film To Warp?

This is topic What Causes A Film To Warp? in forum 16mm Forum at 8mm Forum.

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Posted by Maurice Leakey (Member # 916) on September 09, 2013, 04:42 AM:

What causes a 16mm film to warp? Is it bad storage, too hot, to cold, too humid, too dry? Perhaps badly wound on its spool or core?

With regards to IB Technicolor, I am aware that it is due to the shrinkage in differing stages of its different dyes.

Posted by Robert Crewdson (Member # 3790) on September 09, 2013, 10:03 AM:

The only warping I noticed was on a 16mm film from 1929. The problem was the cement splice, the rest of the film was OK. Lubricating the film would make it more flexible after a period.

Posted by Maurice Leakey (Member # 916) on September 09, 2013, 10:33 AM:

You are very lucky. A large number of 16mm in my collection have varying degrees of warp, only my Bell & Howells are happy to run and take them up tightly.

Posted by Robert Crewdson (Member # 3790) on September 09, 2013, 10:51 AM:

I have look in my copy of Cine Photography for Amateurs, by J.H. Reyner (1931), but he only mentions lubricating to stop the film becoming brittle and breaking. If you films haven't shrunk, I think you could reverse the problem by lubricating, but that's only an opinion. I used to be surprised when I fist took up cine in the 70s that some of the Mountain films appeared rather dry and made a lot of noise running through the projector; I noticed only a few days after lubricating that they were more supple.

Posted by Maurice Leakey (Member # 916) on September 09, 2013, 11:42 AM:

I am referring to films which are warped when purchased, and there appears little to be done to effect a cure, other than to live with it.
There was one possible suggestion, to rewind with the film "turned over" and leave for a while. The time of the "while" was never mentioned!

Posted by Michael O'Regan (Member # 938) on September 09, 2013, 12:58 PM:

I thought that warping was caused by natural shrinkage over time. Am I wrong?

Posted by Robert Crewdson (Member # 3790) on September 09, 2013, 01:29 PM:

Maurice, couldn't find an answer to your problem, and never bought a film that was warped myself. I cam across one site that said it was a sign of acetate stock deteriorating, like vs.

This is all I have found so far, they are suggesting warping is caused by keeping films in damp conditions, garden sheds, etc. I saw a Bell & Howell 16mm in a wooden blimp case that had been in a damp place, the case was in a right mess, and it was being auctioned. I didn't hang about to see if it sold.

http://www.super8.co.uk/film_cleaning_for_8mm_16mm_cine_film.htm

Posted by Jon Byler (Member # 3933) on September 19, 2013, 02:57 PM:

it seems like a film that isn't wound tight enough and then subject to humidity changes would be the main culprit. I couldn't tell you weather it's a too wet or too dry thing one way or another, but it seems like the film would curl towards the emulsion side as it shrinks and dries faster than the base material (if I remember from my film photography days). I'm not sure off the top of my head how much the acetate base films are able to absorb/loose moisture, but most materials can and do to some extent. The gelatin emulsion definitely absorbs moisture.

In general, a tighter wind is going to give less curl, I would think, but if one winds too tight, there is the risk of scratching/stressing/etc.

everything in moderation!

Posted by Michael O'Regan (Member # 938) on September 19, 2013, 03:01 PM:

Ahem....so, aging has nothing to do with it??
[Big Grin]

Posted by Jon Byler (Member # 3933) on September 19, 2013, 03:10 PM:

sure aging will have something to do with it. especially aging in improper conditions!

This description from the wikipedia is interesting:

http://en.wikipedia.org/wiki/Cellulose_acetate_film

they state that as the cellulose acetate film stock deteriorates *it* shrinks, while the emulsion does not.

also interesting is the discussion of the pink color, and where that comes from. I always though that was from the other color fading, rather than the pink color showing up.

-Mann kann doch nie auslernen!

Posted by Bill Brandenstein (Member # 892) on September 20, 2013, 10:58 AM:

Jon, I think the pink & blue hues mentioned as coming from antihalation dyes have to do with still photography and not motion picture prints. So these pink hues aren't related to Eastman's unbeloved "MagentaScope" color fade, which seems to be completely unrelated to vinegar syndrome.

Gotta love film chemistry and all its many potential problems.

Sounds like warp is caused one or more of the following: excess humidity; improper wind; lack of a balance stripe on magnetic sound films; and vinegar syndrome, which ALL acetate film will eventually suffer from.

By the way, Maurice: I've been experimenting with some VS film with enough curl or warp to make the focus unsteady. If you store them with a snug wind turned over, and possibly even tails out, expect to see some improvement only after storing it this way for months, maybe even a year. However, if you can soak it in FilmRenew, you might only need 2-3 months to see a (temporary?) cure. After wetting or soaking for 8-12 weeks or more, wind it correctly and snug - but still very wet - and dry to open air for 2 weeks. At least that's what my early results suggest.

Posted by Lee Mannering (Member # 728) on September 26, 2013, 07:06 AM:

Shrinkage
Shows up worst on Standard 8 as the sprocket holes are big and the film width is small, so as the film mass shrinks the area with the sprocket holes does not purely because there are gapes (holes) hence the bend.

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